You earned a $15,000 bonus. It hits your account as $9,500 and you feel cheated. The reality: $3,300 went to federal withholding (22% flat), $800 to state tax, $1,150 to FICA, and depending on your bracket you might still owe another $1,500 at tax time. The good news is the math is predictable. The better news is the shortfall can earn 4-5% interest in a high-yield savings account between now and April.
- 1.Federal withholding on bonuses is a flat 22% (37% above $1 million per year per employer) under IRS supplemental wage rules.
- 2.Bonuses are also subject to Social Security (6.2% up to wage base), Medicare (1.45% + 0.9% above $200K/$250K), and state income tax.
- 3.Total combined withholding on a typical bonus runs 35-45% of the gross amount.
- 4.Anyone in the 24%+ federal bracket is under-withheld on bonuses; the shortfall is owed at April filing.
- 5.Setting the shortfall aside in a HYSA at 4-5% APY earns $200-$1,000 in interest before you actually owe it.
Why Your Bonus Looks Different in the Bank
When you receive a bonus, you're getting paid supplemental wages — a category the IRS defines separately from regular wages. The withholding rules are different, and the result is the math most employees find confusing.
Three layers of withholding hit every bonus:
Layer 1: Federal income tax. Flat 22% on bonuses under $1 million per year per employer. 37% on the portion above $1M. This is set by IRS rules (Publication 15) regardless of your actual tax bracket.
Layer 2: State income tax. Varies by state. Some states (like California's 10.23% and New York's 11.7%) require flat supplemental withholding rates similar to federal. Others use your normal state withholding rate. Nine states (Texas, Florida, Washington, Nevada, South Dakota, Alaska, Tennessee, Wyoming, and parts of New Hampshire/Tennessee for wages specifically) have no state income tax at all.
Layer 3: FICA. 6.2% Social Security on wages up to the annual wage base ($168,600 for 2024, indexed). 1.45% Medicare on all wages. An additional 0.9% Medicare on wages above $200K single / $250K married — withheld by your employer once cumulative wages cross $200K with that employer.
On a $15,000 bonus paid mid-year to a single tax filer earning $120K base salary in New York:
| Withholding type | Rate | Amount |
|---|---|---|
| Federal (supplemental flat) | 22% | $3,300 |
| New York state (supplemental) | 11.7% | $1,755 |
| Social Security (under wage base) | 6.2% | $930 |
| Medicare | 1.45% | $217.50 |
| Total withheld | ~41% | $6,202.50 |
| Net to your account | $8,797.50 |
Add NYC for residents and the bite gets worse. Different states swap out the middle row; the rest is the same.
The Withholding Gap: Why You May Owe MORE
The 22% federal flat rate matches your actual federal tax exactly only if you're in the 22% bracket. Single filers earning $48,475 to $103,350 are in this bracket; everyone else is mismatched.
Higher-income employees are under-withheld — the 22% covers less than their actual marginal rate, so they owe the difference at April filing. Lower-income employees may be over-withheld and get a small refund.
Here's the federal-only true-up math on a $15,000 bonus by bracket:
| Federal bracket | Actual federal tax | Withheld (22%) | True-up at filing |
|---|---|---|---|
| 12% | $1,800 | $3,300 | −$1,500 (refund) |
| 22% | $3,300 | $3,300 | $0 (wash) |
| 24% | $3,600 | $3,300 | $300 owed |
| 32% | $4,800 | $3,300 | $1,500 owed |
| 35% | $5,250 | $3,300 | $1,950 owed |
| 37% | $5,550 | $3,300 | $2,250 owed |
State true-ups stack on top in states where state supplemental withholding is also flat or below your marginal state rate. California, New York, Massachusetts, and other high-tax states have similar dynamics at the state level.
Run Your Specific Numbers
Calculator "bonus-tax" not found.
The "Federal True-Up" row tells you what you owe (positive) or what you'll get back (negative) at tax time. The "Net Bonus You Keep" row is what hits your bank account — already after all the withholdings, but before any April true-up.
When Bonuses Trigger Bigger Surprises
Three scenarios push the math further from intuition.
Scenario 1: Year with multiple bonuses across the $1M threshold. If you receive cumulative supplemental wages over $1M from one employer in a calendar year, the rate jumps to 37% on the excess. Senior executives often see this in years with both a regular bonus and equity vesting. Plan accordingly — the bracket math is unusual at this level.
Scenario 2: Bonus pushes your total income across a bracket boundary. A $50K bonus on top of $190K base income takes you from the 24% bracket (ends at $197,300) deep into the 32% bracket (starts at $197,300). Your last $40K of bonus income is taxed at 32% — but only 22% was withheld. Result: ~$4,000 owed at filing for the bracket transition alone.
Scenario 3: Bonus pushes you over the Additional Medicare Tax threshold. If your total income for the year crosses $200K single / $250K married, the additional 0.9% Medicare tax kicks in retroactively to dollar one above the threshold. Your employer is required to start withholding it after your cumulative wages cross $200K with them. If you have multiple W-2 sources or significant non-wage income, you may owe the additional 0.9% even when no single employer crossed the threshold — to be reconciled on Form 8959 at filing.
If your employer adds the bonus to your regular paycheck (rather than issuing it as a separate check), they may use the aggregate withholding method instead of the flat 22% supplemental rate. The aggregate method annualizes your total period income and applies your normal W-4 calculation. For high earners, this typically withholds more than the flat 22% — closer to your actual marginal rate. The result: less true-up surprise but smaller bonus deposits. Read your pay stub to confirm which method was used.
What To Do About the Shortfall
What to Do Now
The Underpayment Penalty (and How to Avoid It)
If you owe more than $1,000 at filing AND your withholding/estimated payments don't meet a safe harbor, the IRS charges an underpayment penalty — currently 8% annualized, calculated quarter by quarter on the shortfall.
You're safe if any of these is true:
- Total tax owed at filing is under $1,000
- Your total withholding + estimated payments equals at least 90% of the current year's tax liability
- Your total withholding + estimated payments equals at least 100% of last year's total tax — or 110% if last year's AGI was over $150,000
The third option is the simplest for predictable earners. Make sure your annual withholding plus estimated payments equals 110% of what you paid last year, and the IRS leaves you alone — even if your current-year bonus or RSU vest creates a massive April bill.
If you blow through the safe harbor, the penalty is unavoidable — but it's still cheaper than expecting it. Plan ahead by mid-year if you know a big bonus is coming.
Why Companies Use the 22% Rate (Even When It's Wrong)
The 22% flat federal rate is an administrative simplification. Calculating each employee's true marginal rate would require the company to know your spouse's income, other tax credits, deductions, and any non-wage income — none of which they have access to.
The flat 22% was set to be approximately right for the median bonus recipient at the time the rule was written. It's not personalized; it's standardized. Some employers offer the aggregate method as an option, particularly for high earners. Most don't.
The IRS could solve this by requiring employers to use the aggregate method by default and the flat method only as an option. They haven't, because the flat rate is simpler to administer and the under-withholding problem mostly affects high earners who can absorb the timing mismatch — they don't need an interest-free loan from the government.
Common Mistakes
Mistake 1: Thinking the withholding is the tax. It isn't. The 22% federal is just an estimate of your liability. Your actual liability is whatever your marginal rate produces. The withholding either over- or under-pays the actual tax, and the difference is settled in April.
Mistake 2: Assuming the bonus "is taxed differently." It's not. Bonuses are taxed at exactly the same rates as your regular salary once everything reconciles in April. Only the withholding is different. If you ignore withholding and look at total annual income vs total annual tax, bonus money is treated identically to salary money.
Mistake 3: Not adjusting for state. California's flat 10.23%, New York's 11.7%, New Jersey's 9.75%-10.75%, and similar state supplemental rates often over-withhold below the top bracket and under-withhold at the top. State true-ups can be larger than federal in high-tax states.
Mistake 4: Spending the gross. A common pattern: bonus check arrives, employee plans a $15K renovation, finds out the net is $9K and the renovation has to be cut. Always plan against the net, and remember the net is before any April true-up.
- ✦Bonuses are 'supplemental wages' and federally withheld at a flat 22% (37% above $1M per year per employer). Add state and FICA and total withholding is 35-45% on most bonuses.
- ✦The 22% federal withholding under-pays your actual federal tax for anyone in the 24%+ bracket. The shortfall ('true-up') is owed at April filing.
- ✦On a $15K bonus at the 32% federal bracket, the federal shortfall is exactly $1,500 — plus any state shortfall and the 0.9% additional Medicare if applicable.
- ✦Safe harbor against underpayment penalty: ensure total withholding + estimated payments equals 110% of prior year's total tax (100% if AGI was under $150K).
- ✦Park the shortfall in a high-yield savings account at 4-5% APY between bonus payment and April. Earns interest on money you'd otherwise prepay.
Related Calculators and Guides
- Bonus Tax Calculator — exact federal, state, FICA, and true-up math for your specific situation
- RSU Tax Guide — same withholding-gap dynamic for restricted stock units
- Paycheck Calculator — for regular wage tax planning
- Year-End Tax Moves — pre-December actions to reduce taxes
- Compare HYSA Rates — where to park the shortfall while you wait for April
Sources: IRS Publication 15 (Employer's Tax Guide), IRS Revenue Procedure 2025-32 (2026 inflation adjustments), California EDD and NY DTF supplemental withholding tables. This guide is for educational purposes and does not constitute tax advice. Consult a CPA for your specific situation.
Frequently asked questions
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